Brazil's render engine uses the raytracing method (as opposed to scanline or hardware renderers). Raytracing has the advantage of simulating the way photons actually behave; although raytracing is not limited to realistic solutions.
Brazil's advanced raytrace engine simulates a wide range of effects including:
- Refraction (transparency)
- Dispersion (prismatic rainbow effects)
- Sub-surface scattering (diffuse light transmitting materials such as wax or skin)
- Glossy reflections (blurry or brushed materials)
Rhino supports point, spot, directional, linear, and rectangular light objects with simple properties such as color, hotspot, and shadow casting. Brazil adds about 100 more light properties. The number of light properties can be intimidating, but most of these settings are only needed in a few specific cases.
Brazil light features include:
- Decay (darkening of light as a function of distance to the source)
- Attenuation (amplification of brightness as a function of distance to the source)
- Focus control (rectangular, conical, cylindrical etc.)
- Projections (emitting a picture or procedural texture instead of a color)
- Exclusion lists (lights ignore specified objects in the scene)
Brazil will also display focal cones and attenuation spheres for selected lights in the viewport, so you can see the affects of your settings in real-time.
Toon and NPR
Brazil includes non-photoreal (NPR) effects such as toon shaders.
(Car)Toon shaders cooperate with photoreal shaders so you can mix glass, brushed metal and toon in a single scene without losing the ability to do indirect-illumination, depth-of-field or any other effect.
You can specify the behaviour of fills and inks including:
- Multi-level paint fills (discrete colors applied based on luminosity)
- Gooch type fills, (continuous gradient)
Depth of Field
Depth-of-field (DOF) simulates the imperfect focusing properties of physical lens-systems such as biological eyes and cameras. DOF adds a measure of realism to a rendering by blurring out-of-focus areas. It can also be used to "mask" areas of the scene such as distant surroundings.
The settings for DOF include:
- Focus distance
- Bokeh abberations (the effect over-exposed areas in an image have when they are out of focus)
Depth of Field Details
Rhino viewport screenshot. Brazil materials can be simulated and displayed in the real-time viewport.
Brazil rendering with no DOF effect. Everything is in focus.
Depth of field enabled.
DOF with focal distance aimed at the first glass.
The middle glass is in focus. The depth-of-field effect blurs both objects in front of and behind the field.
The field is centered around the third object.
Brazil supports both bitmap and procedural textures. Bitmap textures use images (a grid of colored pixels). Procedural textures, on the other hand, are defined by a mathematical function. Procedural textures do not suffer from resolution or tiling problems, and it is easy to change their behavior. Procedural textures are simulated in the Rhino viewport to make adjustments easy.
Brazil built-in functions:
Advanced definitions can be used to create other realistic materials such as wood and stone.
High Dynamic Range colors
Brazil is a high-dynamic-range (HDR) engine.
With an HDR rendering engine, colors are not limited to the black~white range. Colors can be brighter than white and darker than black. "Brighter-than-white" colors are important even though the computer screen cannot display them, because colors in a rendering are often diluted by partial reflection or refraction.
High-dynamic-range color details
No high-dynamic-range colors. The material on the ball is partially reflective, which means that the residual color after reflection is about one-fourth of what it used to be.
The white planes reflected in the ball have been given a brighter-than-white color.
The planes are ten times brighter than white, so the resulting color is also brighter than white. It is limited by the gamut of the computer screen. A glowing effect would visually enhance the brightness, is not actually possible to display this rendering accurately.
Influence of indirect lighting
Colors can also be diluted through indirect lighting. This scene is lit both directly (through a pointlight to the left, which casts the predominant shadow) and indirectly:
If the brightness of the tube is set to zero, then it will be completely black, and only the direct light emitted from the pointlight object plays a role in this scene.
The brightness of the tube has been set at half the normal brightness, meaning that the purple-to-pink gradient on the tube appears half as dark. However, there is already some indirect pink discoloration on the ground surrounding the tube.
When the brightness is set to 1.0, we see the gradient fwith a substantial amount of indirect pink, especially on the ground inside the tube walls, which is exposed from all directions. At this point, this scene is not yet HDR.
When we boost the brightness of the tube to twice its normal color, the far end of the tube (which is supposed to be pink) has been boosted so far that it becomes brighter than white. It's still pink, but too bright to be represented properly on the screen.
When we boost the brightness to a factor of five, the brighter-than-white boundary is located further towards the dark end of the gradient. Also, the indirect lighting is now predominant on the ground near the tube to the point that some of it has also breached the white barrier.
The brightness is set to one again, but the strength and saturation of the indirect lighting has been boosted. This creates a physically incorrect scene that uses the HDR features of Brazil without specifying HDR colors.
Global Illumination is a feature you will find in most modern rendering platforms including Brazil.
Global Illumination uses both direct and indirect illumination to generate a realistic image. Direct illumination is the process where light objects cast light onto objects creating bright areas on surfaces that face the light source, darker areas on surfaces that do not face the light source, and shadows when surfaces cannot "see" the light source directly due to some obstruction. After a surface has been lit directly, it emits photons and some of those photons are captured by other surfaces and some of those photons are finally caught by our eyes or a camera. The effect of indirect illumination is relatively small compared to that of direct illumination. Yet, it is very important to the "realistic" quality of the image.